Curative treatment of local and/or regional breast cancer requires surgery and adjuvant therapy such as thermotherapy. In thermal treatment of breast cancer, the tissue is exposed to high temperatures that damage and kill cancer cells with minimal injury to normal tissues. The overall goal of our research program is to develop an image-guided, molecular specific photothermal therapy of cancer using targeted metal nanoparticles. Specifically, using targeted plasmonic nanosensors and an advanced, in-vivo, noninvasive, functional, molecular specific imaging technology (i.e., integrated ultrasound, photoacoustic and elasticity imaging), photothermal therapy can be greatly improved. Indeed, before the therapeutic procedure, using ultrasound (anatomical and blood flow imaging) and elastography (biomechanical functional imaging), the tumor will be non-invasively imaged to develop an appropriate treatment plan. Furthermore, the delivery and interaction of molecular specific photoabsorbers with cancerous tissue will be imaged using photoacoustics - a technique capable of in-vivo imaging of plasmonic nanoparticles at sufficient depth. During the therapy, the real-time imaging system will be used to guide photothermal therapy by tracking the temperature rise and, therefore, monitoring cancer treatment. Finally, after the therapy, the combined imaging will be used to accurately assess the short-term and the long-term treatment outcome. The central theme of the current application is threefold: to develop multifunctional plasmonic nanoparticles acting as both photoabsorbers for photothermal therapy and contrast agent for molecular and thermal imaging; to design and build a laboratory prototype of the integrated ultrasound, photoacoustic and elasticity imaging system; and to initially test the developed nanoparticles and imaging technology in 3-D tissue phantoms and small animal cancer model ex vivo and in vivo. Therefore, all theoretical and experimental studies will be conducted to evaluate the applicability of the molecular specific, image-guided photothermal therapy to treat cancer. At the end of the study, we will outline the design and technical specifications of a clinical image- guided photothermal therapy system.